The present invention relates to a pipe coupling according to the preaamble of claim 1.
A pipe coupling of this type is known from DE-A-27 31 465 or from the corresponding U.S. Pat. No. 4,119,333. The sealing lips of this coupling extend toward each other, and they are included in an elastomer sealing sleeve of C-shaped cross section, which is supported against the sleeve bar by means of a coil-spring ring which is pre-tensioned in the peripheral direction. This configuration of the sealing lips support limits the upper permissible operating temperature of the pipe coupling, since, under extreme temperatures, there is a danger that thermal expansion, which acts in addition to the pressure expansion of the sleeve when the housing is compressed, will cause the sleeve material to flow between the windings of the coil-spring ring. Although the coil-spring rings are at least partially able to equalize the swelling and shrinkage of the sleeve material, flow of the sleeve material can result, under extreme operating temperatures and long periods of pressure, in the sealing capacity of the pipe coupling declining as it subsequently cools down to lower temperatures and low pressure.
In the case of pipe couplings as known, for example, from DE-A-24 28 101 or from the corresponding U.S. Pat. No. 3,877,733, each of the sealing lips is supported by means of a respective torus formed onto the sleeve bar. In this type of sleeve configuration, the flow of the material under long periods of pressure and high operating temperatures can certainly be prevented, but there is a danger of a sealing lip sticking to the respective torus, which may hinder the optimal adaptation of the sleeve to the respective operating conditions.
Based on this prior art, an object of the present invention is therefore to refine the pipe coupling of the generic type in such a way that it is suitable for use at higher operating temperatures.